In general, in a power system, a voltage of a power system is controlled by a control device such as a Step Voltage Regulator (SVR) or a Static Var Compensator (SVC).
A so-called centralized control, in which a monitor control server collectively grasps a state of an entire power system and applies an optimal control instruction to each control device, is disclosed in PTL 1.
A technique, in which in a case where reactive power passing through the SVR is monitored and the reactive power is continuously measured for a predetermined time or longer, the SVC is estimated to be in operation, and tap switching control of the SVR is performed, is disclosed in PTL 2. The technique is a so-called autonomous distributed control technique in which communication is not assumed.